A master electrician is installing a fire alarm system in a new school building. The fire alarm control unit (FACU) requires a dedicated branch circuit. Which of the following statements regarding the fire alarm system's power supply is correct according to NEC Article 760?
- AThe fire alarm system's primary power can be supplied by the general lighting branch circuit, provided it is the first load on the circuit.
- BThe branch circuit for the FACU must be dedicated, identified as 'FIRE ALARM CIRCUIT,' and not supplied through a GFCI or AFCI device.
- CThe overcurrent protective device for the FACU's branch circuit must be readily accessible to all building occupants for quick shutdown.
- DThe branch circuit for the FACU must be rated at least 15A and supplied from the emergency panelboard.
Show answer & explanationAnswer & explanation
Correct answer: B. The branch circuit for the FACU must be dedicated, identified as 'FIRE ALARM CIRCUIT,' and not supplied through a GFCI or AFCI device.
NEC 760.41(B) and 760.121(B) specify that the branch circuit supplying the fire alarm system must be dedicated solely for the fire alarm system, permanently identified at the supply end, and not supplied through a ground-fault circuit interrupter or arc-fault circuit interrupter.
Why the other options are wrong
- A. The fire alarm system requires a dedicated branch circuit, meaning it cannot share with general lighting or other loads (NEC 760.41(B)).
- C. The OCPD for the FACU should be accessible to authorized personnel, not 'all building occupants,' to prevent tampering or accidental shutdown (NEC 760.41(B)).
- D. While a 15A circuit might be sufficient for some FACUs, the NEC does not mandate it be supplied from an emergency panel unless it's part of an emergency system, and the identification/GFCI/AFCI rules are more critical.
Fire Alarm Power Supply (NEC)
The NEC mandates specific requirements for the primary power supply of fire alarm systems, including a dedicated, identified branch circuit that is not interrupted by ground-fault or arc-fault protection, to ensure system reliability during emergencies.
- Dedicated branch circuit.
- Permanently identified at supply end.
- No GFCI or AFCI protection allowed.
- Overcurrent protection accessible only to authorized personnel.
Memory trick: Fire Alarm Power: Dedicated, Labeled, and Never GFCI/AFCI.